NATUEE OF FLUID CRYSTALS 181 



Here, then, for the first time, we gain a satisfactory physical 

 explanation for the doubly refractive globules seen in, or ob- 

 tained from, the organism ; they are fluid sphere-crystals. 



CAN WE PROCEED ANY FURTHER ? 



As I have already stated, the investigation of compounds 

 presenting this intermediate stage is a recent study, the number 

 found is increasing with relative rapidity, and it is well within 

 the bounds of the possible that yet other substances, constituents 

 of the normal organism, will be found to possess it. But what 

 is not a little suggestive is that the physicists, without any 

 thought of physiologic problems, have already noted its existence 

 in two groups of bodies which are normally represented in the 

 organism, namely, the cholesterin compounds and the oleates. 

 And studying the list of crystalline fluids and the temperatures 

 at which the intermediate stage manifests itself, with the excep- 

 tion of one group these bodies pass into what, for convenience, 

 I term the intermediate stage at temperatures far above that 

 of the room or body ; thus save for that one group they cannot 

 be responsible. The only group containing members which 

 afford doubly refractive globules at room temperature is that 

 of the compounds of oleic acid. These compounds are so unstable 

 the oleic acid so readily undergoes dissociation that it is 

 hopeless or almost hopeless to gain them in a pure state, and as 

 a consequence it is not possible to state with precision what are 

 the points of melting and clearing. But certainly cholesteryl 

 oleate is viscid and buttery at the room temperature, and at this 

 can be demonstrated to afford the globules, and the simple 

 oleates of ammonium, potassium, and sodium may likewise con- 

 tinue to manifest them at the room temperature, 1 although in 

 general the fields show definite crystals. Here it may be noted 

 that the medium in which the soaps are present is capable of 

 modifying the melting-point. To this fact I shall have to return 

 later. Cholesteryl palmitate and stearate, I have found, both 

 afford these globules and so exhibit the intermediate stage, but 

 their melting-point is very definitely higher. We are led thus to 



1 Evidently these myelin globules of the organism are not doubly refractive 

 at blood heat. I could not demonstrate those of the adrenal in a warm room 

 at the Rockefeller Institute (about 75 F.) until the window had been opened 

 and the room cooled down. 



